Inhaler with acoustic flow monitoring

ABSTRACT

An inhaler or add-on device for an inhaler for dispensing a medicament to be inhaled. The inhaler or add-on device has a housing (H) with an air inlet (A_I), and an air outlet (A_O) for outputting air to be inhaled by a user. The housing (H) defines a flow path (FP) between the air inlet (A_I) and air outlet (A_O), and a passive acoustic element (PAE) is arranged in this flow path (FP) inside the housing (H). The passive acoustic element (PAE) has a structure having one or more structured gaps arranged to be passed by an air flow and it is dimensioned such that air flow passing it will generate sound (S) with pre-determined characteristics depending on the air flow speed. This allows acoustic monitoring of air flow passing the first passive acoustic element (PAE) external to the housing (H) by capturing and processing sound generated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of and claims the benefit andpriority to U.S. patent application Ser. No. 16/624,826, filed on Dec.19, 2019, which is a U.S. National Phase Application of PCTInternational Application Number PCT/DK2018/050164, filed on Jun. 22,2018, designating the United States of America and published in theEnglish language, which is an International Application of and claimsthe benefit of priority to Danish Patent Application No. PA 2017 70492,filed on Jun. 23, 2017. The entire contents of the above referencedapplications are hereby expressly incorporated by reference in theirentireties. Any and all priority claims identified in the ApplicationData Sheet, or any correction thereto, are hereby incorporated byreference under 37 CFR 1.57.

FIELD OF THE INVENTION

The invention relates to the field of inhalers for dispensing amedicament for inhalation, e.g. a dry powder or aerosols. Especially,the inhaler relates to inhalers and add-on devices for inhalers capableof determining inhalation flow, and specifically the invention providesan inhaler with a first passive acoustic element for generating soundexternal to the inhaler, to allow monitoring of inhaled flow, e.g. formonitoring an inhaled medicament dose. Specifically, the first passiveacoustic element allows the inhaler to function also for monitoringexhaled air, e.g. for monitoring peak flow.

BACKGROUND OF THE INVENTION

COPD and asthma are examples of lung diseases which require frequent useof inhalation medicaments to improve lung function. However, often theusers of inhaler devices do not use the inhalers in the correct manner.E.g. the user does not inhale a full dose of medicament, or theinhalation is not within the prescribed air flow speed. Thus, to ensurecorrect use, monitoring of the inhalation process can be used to guidethe user in correct inhalation behaviour. Further, the users may forgetor not be able to take their dose at the prescribed frequency and timingand thereby result in non-adherence or non-compliance.

Inhaler devices exist which are capable of tracking a user's inhalationof medicament, e.g. by means of built-in electrical sensors for sensinginhalation air flow speed, and an associated processor device forprocessing signals from the sensors accordingly, e.g. so display to theuser if an inhalation was successful, or if the air speed was too weakor too strong etc. However, such devices are often expensive andcomplicated, or they may be complicated to use, e.g. they may requirereplacement or charging of batteries.

SUMMARY OF THE INVENTION

Following the above, it may be seen as an object of the presentinvention to provide a simple inhaler that can be used to monitor auser's inhalation of a medicament, in obtaining a desired inhaling airflow speed which can be used in a normal environment. Still further, itwould be advantageous to be able to sense the flow rate duringinhalation, by a user, employing low cost equipment. Still further, itwould be advantageous, if the same device could be used to monitorexhalation function, e.g. monitoring forced exhalation such asdetermining peak flow.

In a first aspect, the invention provides an inhaler add-on device foradd-on to an inhaler for dispensing a medicament to be inhaled, e.g.aerosols or a dry powder, the inhaler add-on device comprising

-   -   a housing comprising an air inlet, and an air outlet for        outputting air to be inhaled by a user, wherein the housing        defines a flow path between the air inlet and air outlet,        wherein the housing is configured for connection to the inhaler,        and    -   a first passive acoustic element arranged in the flow path        inside the housing and dimensioned such that air flow passing        the first passive acoustic element will generate sound with        pre-determined characteristics depending on flow speed of air        passing the first passive acoustic element, so as to allow        acoustic monitoring of air flow passing the first passive        acoustic element external to the housing, wherein the first        passive acoustic element comprises a structure having one or        more gaps arranged to be passed by an air flow, and wherein the        one or more gaps may be shaped and separated by a distance so as        to generate sound depending on air flow speed with        pre-determined characteristics comprising at least spectral        components, e.g. also amplitude. Thus, via designing the passive        acoustic element to provide pre-determined distinct        characteristics, e.g. spectral peaks, the generated sound allows        detection of recognizable characteristics indicative of the air        flow, e.g. air flow speed.

Such inhaler add-on device is advantageous, since it has been proven tobe possible to provide an inhaler add-on device with a very simplestructure, including the passive acoustic element with structured gaps,which allows e.g. 3D printing of the entire inhaler. This allows theinhaler add-one device to be manufactured as a disposable product and/orto be produced at the point of need, e.g. by the user or at a hospitaletc. The inhaler add-on device does not require any electricalcomponents inside or on the housing, since the sound is generated by apassive acoustic element, in the same manner as a whistle. Thus, theinvention provides a simple low cost add-on device for existinginhalers, either metered dose inhalers, dry powder inhalers or otherinhaler types. The sound from the add-on device can be captured byexisting processor devices, such as a smart phone with a suitable app.Therefore, the simple add-on device can provide an inhaler user with animportant inhalation guidance together with a processor device alreadyat hand. If preferred, the add-on device may in some embodiments includea microphone and connected equipment to perform sound capturing and atleast part of the necessary processing to determine, and thencommunicate data, e.g. via Bluetooth®, to an external device, such as asmart phone, which can then provide the user with inhalation flowinformation via its display or via an audible message. In someembodiments, the add-on device comprises two separate elements to beattached to an inhaler: one with the passive acoustic element, and onewith a microphone to capture sound from the passive acoustic element andequipment to transmit data via Bluetooth® or wi-fi to an externaldevice. Especially, such microphone device may be attached to theinhaler by means of a rubber band around the inhaler. Compared to soundcapturing with an external device, such add-on attachment device has awell-defined distance to the sound generating passive acoustic element.

It is based on the insight of the inventors, that a simple passiveacoustic element with one or more gaps allows generation of sound withcharacteristics allowing an external device to capture sound, e.g. asmartphone, and to process the captured sound to allow monitoringinhaled air flow during an inhalation, especially in the important airflow speed range 10-100 litres per minute. In typical embodiments, thesound generated will predominantly be transmitted from the passiveacoustic element via the air inlet and since the inhaler can produce asubstantial sound pressure, the sound with the important characteristicscan be captured by a device having a microphone at a reasonable distancefrom the inhaler, e.g. at a distance of 1 cm to 1 m, or such as 10 cm to1 m, or so. This can be achieved by a smartphone, and with the use of asmartphone, data can be stored and e.g. transmitted to doctors and/orhospital etc. Alternatively, a microphone for capturing sound may bepart of the inhaler or such microphone may be placed in an inhaleradd-on device.

Furthermore, the resulting acoustic information in the sound from theinhaler can also be 1) transferred to a Health app, or a correspondingapp on a smartphone (locally), or 2) saved to a central database, cloudor corresponding for further use: including, but not limited todiagnostic, lifestyle monitoring, sport, training, exercise, and socialmedia sharing. The acoustic information can also be used together withsome other breath analysis data, i.e. a broad area of analyticalsciences covering the analysis of exhaled chemical components in theexhaled air. These can be related to several diseases, includinginflammation (asthma), lung cancer, respiratory conditions, but alsoother diseases.

Especially, it is preferred to track spectral components in the soundgenerated during inhalation versus time, during an inhalation, and thishas been found to be sufficient to monitor air flow speed or an inhaledair volume, e.g. to determine if a full dose of medicament has beeninhaled. To do so, a processing algorithm which may be based on patternrecognition and/or machine learning algorithms based on air flow speedtests with a specific implementation of the inhaler, so as to allow thealgorithm to determine air flow speed from acoustic characteristics ofthe sound in the form of amplitude and spectral components, e.g.detection of spectral peaks.

Further, the housing with the flow path and passive acoustic element maybe designed as a stand-alone inhaler, i.e. with a mouthpiece at the airoutlet. However, in other designs, the housing with the flow path andpassive acoustic element can be designed to an attachment, e.g. forclick-locking onto, an existing inhaler device, either upstream ordownstream of the existing inhaler device.

Even further, the inventors have realized that the inhaler can be usedalso to monitor exhaled air, e.g. to use it as a peak flow meter fortesting the user's lung function. This can be done by either reversingair flow compared to inhalation, i.e. by exhaling into the air outlet,or by exhaling into the air inlet. A second passive acoustic element tobe used only in exhalation mode may be used. By capturing soundgenerated by the passive acoustic element in this exhalation mode e.g.by forced exhalation, it is possible to determine one or more parametersindicative of the user's lung function. This is an important feature ofthe inhaler, since the user then only needs one single device formedication as well as to test the lung function, which is important inthe correct medication of a lung disease.

In both inhalation and exhalation mode of operation, a smartphone orequivalent device with a processor and a microphone can be used as anexternal device for capturing sound from the inhaler and performing thenecessary signal processing. Thus, in general no extra, complicated anddedicated equipment is needed for the user to monitor inhalation andexhalation. Further, by using a smartphone or equivalent, the user cancommunicate the results to a medical doctor or hospital.

In the following preferred features and embodiments will be described.It is to be understood that the acoustic features of an inhaler add-ondevice may be built together with or integrated with an inhaler. Thus,in the following, even by referring to an inhaler, the general featuresand embodiments described will apply for such inhaler as well as thespecific embodiments implemented as an inhaler add-on device for add-onto an existing inhaler.

The first passive acoustic element is preferably a non-vibratingstructure arranged to generate sound by movement of air passing thepassive acoustic element.

Preferably, the one or more gaps of the acoustic element are such as0.5-3 mm wide. The length of the gap(s) may be such as 2-10 mm. Materialthickness around the gap(s) is preferably 0.5-3 mm. Preferably, thegap(s) have rather sharp edges, such as edges formed by 90° corners, orat least corners of such as 40°-140°, or such as 70°-110°. E.g. this canbe obtained in a manufacturing process by 3D printing the passiveacoustic element with a 3D printing resolution better than such as 200μm, preferably better than 100 μm. The inhaler is suited to be 3Dprinted, since it is possible to print it monolithically in spite of arather complex inner geometry, including the passive acoustic elementwith structured gaps to produce the acoustic output. The gap(s) may berectangular in shape with a length of 2-5 times the width.Alternatively, the shape may have a length of 2-5 times the width,having two parallel walls, but with one tapered end. Especially, thepassive acoustic element may be formed as one or two rows ofsubstantially rectangular shaped parallel gaps, each having a length ofat 2-5 times the width. Preferably, the air flow direction for airpassing the gap(s) is perpendicular to a length axis of the gap(s).

Especially, the one or more gaps may be shaped and separated by adistance so as to generate sound depending on flow speed withpre-determined characteristics comprising at least one spectral peak, ortwo to four spectral peaks. The sound may vary in dependence of air flowspeed by variation in amplitude and/or frequency of such spectral peaks.Spectral peaks (pure tones) in the sound are rather easy to detect evenin a noisy environment, thus allowing practical use of the inhalerwithout requiring especially quiet environments.

The first passive acoustic element may have surfaces in or adjacent tothe one or more gaps which have surface morphology (e.g. in micro meterscale, “micro-structuring”) and surface material, which can both beselected depending on the type of gap(s) selected and which specificsound is preferred. In other words, the “micro-structure” of the varioussurfaces of first acoustic element will influence the air flow aroundthe gap(s) and thus also the generated sound.

The first passive acoustic element may be designed to generate soundpredominantly within an audible level and in an audible frequency range,thereby allowing the user to hear tones indicative of inhalation airflow speed. It may alternatively be preferred to design the firstpassive acoustic element so as to generate sound predominantly withfrequencies above 14 kHz, so as to be generally inaudible, thus allowingthe inhaler to be used in public without generating any offensive ordisturbing tones. Still further, the first passive acoustic element maybe designed to generate sound with audible and inaudible spectralcomponents for air flow speeds in the relevant range for inhalation.

The flow path and the passive acoustic element are preferably designedso as to generate sound with detectable pre-determined characteristicsfor air flow speeds at least within the interval 20-90 litres perminute, preferably within the interval 10-100 litres per minute, therebyallowing processing of relevant inhalation air flow speeds of a humanuser. This has been proven possible by the inventors with rather simpledesigns, even to allow individual adaptation of the passive acousticelement to the lung capacity of the user.

In preferred embodiments, the first passive acoustic element has aplurality of gaps, e.g. 2, 3, 4, 5 or more gaps, which are separated bya distance (seen in the direction of air flow), e.g. the first passiveacoustic element may have a plurality of sets of gaps separateddifference distances. E.g. the first passive acoustic element may have aplurality of gaps with identical heights and lengths, and/or a pluralityof gaps with different heights and lengths. Especially, the one or moregaps may be straight gaps which are perpendicular or substantiallyperpendicular to a direction of air flow passing the first passiveacoustic element.

In preferred embodiments, the first passive acoustic element comprises astructure having teeth defining one or more gaps between them, whereinthe one or more gaps being a passage through the structure with nomaterial being present in the gap. Especially, the gaps are a series ofgaps defined within a hollow structure guiding the air flow. The hollowstructure may especially have plane upper and lower parts, and air flowis guided parallel with these upper and lower plane parts.

At least one tube element may be arranged inside the housing and havingone end connected to the air inlet or air outlet, e.g. two or more tubeelements may be arranged inside the housing and forming part of the flowpath to let air flow pass the first passive acoustic element.

In some embodiments, the air inlet is arranged at a bottom part of thehousing, wherein the air outlet is arranged at a top part of thehousing. Especially, the first passive acoustic element may be arrangedso between the air inlet and air outlet, that a direction of air flowpassing the first passive acoustic element is perpendicular to orsubstantially perpendicular to a direction of air entering the airinlet. Especially, the first passive acoustic element may be arranged sobetween the air inlet and air out, that a direction of air flow passingthe first passive acoustic element is perpendicular to or substantiallyperpendicular to a direction of air exiting the air outlet.

The first passive acoustic element can be positioned in the flow pathupstream or downstream of an inhaler medicament compartment forproviding medicament to be inhaled. Especially, the medicamentcompartment may be a multi dose chamber or capsule, or a single dosechamber or capsule. As an alternative, the first passive acousticelement and an inhaler medicament compartment for providing medicamentto be inhaled are arranged in respective parallel flow paths. E.g. theair inlet is split into two separate openings each guiding air to therespective parallel flow paths. This allows freedom to design the flowpath around the passive acoustic element irrespective of the inhalationflow path.

Breaking a capsule by a mechanism (small needle) inside the inhaler toallow inhaling the medicament from the capsule, and this process willalso make a sound, which can be used to detect, whether the capsule wasfully functional and/or properly stored. Thus, further analysis of soundfrom the inhaler may be used to provide additional information regardingthe use of the inhaler.

A second passive acoustic element may be positioned at a differentlocation inside the flow path than the first passive acoustic element.Hereby, additional sound components or characteristics can be generated,e.g. for facilitating the processing of sound to arrive at a measure ofair flow speed.

In some embodiments, the inhaler is arranged for positioning of aninhaler medicament capsule inside the housing, so as to allow inhaling amixture of air and medicament released from the said capsule via the airoutlet. Especially, the inhaler is arranged to be opened and closed by auser's hand or hands, so as to allow insertion and replacement of aninhaler medicament capsule, e.g. a top part of the housing may bearranged for being taken off and put back on by the user.

In some embodiments, the inhaler is a multi dose disposable inhalerwhich is manufactured with multiple medicament doses inside the housing,and when all doses have been inhaled, the inhaler can be discarded. Suchembodiment may be designed so that it cannot be opened by the user, i.e.without any tools. In some embodiments, the housing and the firstpassive acoustic element is formed as a monolithic element, such asformed as one single polymeric material.

In embodiments, the air inlet or air outlet of the housing is arrangedfor connection to a separate device, wherein said separate devicecomprises a compartment comprising a medicament to be inhaled. I.e. insuch embodiments, the housing and passive acoustic element etc. thereinis an add-on to an existing inhaler device, e.g. reusable ornon-reusable inhaler, that being single dose or multi dose devices.

Specifically, in an inhaler add-on embodiment, the housing has a mouthpiece in one end, and a fitting part at the opposite end, wherein themouth piece is arranged for contact with the user's mouth duringinhalation, and wherein the fitting part is arranged for connection tothe inhaler by attachment of the fitting part to an air outlet of theinhaler. E.g. the fitting part may be arranged to lock a position of theinhaler add-on device to the inhaler. Specifically, the fitting part maybe shaped so as to receive an air outlet pipe of the inhaler and toallow locking of the position of the inhaler add-on device to theinhaler upon insertion of the outlet pipe of the inhaler into thefitting part of the inhaler add-on device. The fitting part may haveother means for attachment to the inhaler, e.g. using a magnet,protrusions/indentations serving for click locking etc. The mouth piecemay have a first outer cross sectional area, and wherein the fittingpart has a second outer cross sectional area being larger than the firstouter cross sectional area of the mouth piece. In this way the add-ondevice is shaped to provide a tight fit when pressed onto the inhaler.Specifically, the mouth piece may have a circular or elliptical outercross sectional shape.

The housing of such inhaler add-on device may be shaped to provide astraight flow path between the mouth piece and the fitting part.Specifically, the first passive acoustic element may be arranged insidethe mouth piece and with one opening connected to the opening of themouth piece, wherein an opposite opening of the first passive acousticelement is connected to a flow path inside the housing. If preferred thefirst passive acoustic element may be placed inside the housing in anintermediate part of the housing between the mouth piece and the fittingpart of the housing.

In an inhaler add-on embodiment, the first passive acoustic element isarranged in a flow path so as to receive a limited part of an air flowthrough the mouth piece. E.g. such limited part of the air flow may besuch as 2-80%, such as 5-50%, such as 10-30%, of an air flow through themouth piece. Hereby, the passive acoustic element can be kept away fromthe main flow of medicament, which can be advantageous. Further, thelower flow that needs to pass the acoustic element can be advantageous.Specifically, the first passive acoustic element may be arranged in anair flow path between an opening of the housing and air flow inside thehousing, wherein the opening of the housing is separate from the mouthpiece and the fitting part. Specifically, the first passive acousticelement may be arranged in a flow path with a direction which isperpendicular to a flow path direction in the mouth piece.

An inhaler add-on embodiment comprises a second passive acoustic elementwith one or more gaps shaped and separated by a distance so as togenerate sound depending on air flow speed with pre-determined spectralcomponent characteristics. Specifically, the second passive acousticelement may be arranged to provide spectral component characteristicsdifferent from the first passive acoustic element.

In an inhaler add-on embodiment, the mouth piece may be arranged toreceive exhaled air, so as to allow acoustic monitoring of exhaled airflow external to the add-on device upon a user exhaling air into themouth piece.

In such an inhalation and exhalation embodiment, a first passiveacoustic element may be arranged to generate sound in response toinhaled air flow through the mouth piece, and a second passive acousticelement may be arranged to generate sound in response to exhaled airflow through the mouth piece, i.e. using two separate passive acousticelements. However, it is to be understood that in principle, the firstand second passive acoustic elements may be identical with respect totheir structure. It may be preferred that their structures aredifferent, since the flow speed to be measured during inhalation andexhalation can be expected to be different. In a specific embodiment, afirst valve is arranged to block exhaled air flow from passing the firstpassive acoustic element, and a second valve arranged to block inhaledair flow from passing the second passive acoustic element. This wouldfurther ensure that air flow does not go in the wrong direction in theadd-on device and inhaler and also ensures that the user does not exhaleinto the inhaler, which may otherwise damage the medicine inside theinhaler Specifically, the first and second passive acoustic elements andthe first and second valves may be arranged in the mouth piece.

In an inhaler add-on embodiment, a microphone is arranged to capturesound from the first acoustic passive element, and the embodiment isfurther being arranged to transmit data in response to captured sound bymeans of a wired or wireless connection to an external device, such as asmart phone or other mobile device. Specifically, the microphone, aprocessor circuit connected thereto is arranged to transmit said data,and a battery for powering the processor circuit are housed in a secondhousing separate from the first housing, preferably the second housingis arranged for attachment to the inhaler. Thus, in this embodiment, twoseparate add-on components are to be attached to the inhaler, e.g. thesound generating add-on device to be attached to the outlet pipe of theinhaler, while the sound capturing add-on device is to be attached toanother part of the inhaler, e.g. via a rubber band etc. E.g. aBluetooth® connection to a mobile device, e.g. a smart phone, may beused to transmit recorded sound to the mobile device for furtherprocessing. E.g. the processor circuit is programmed to perform all ofor at least a part of processing required to determine inhalation flowspeed in response to the captured sound.

In some embodiments, the inhaler is further arranged to receive exhaledair via the air inlet or the air outlet, so as to generate sound withpre-determined characteristics depending on flow speed of air passingthe first passive acoustic element, so as to allow acoustic monitoringof air flow passing the first passive acoustic element external to thehousing upon a user exhaling air into the air inlet or air outlet. Thus,this adds another functionality utilizing the passive acoustic elementof the inhaler to generate sound also during exhalation, therebyallowing lung function tests, e.g. FEV1 or peak flow measurement etc.E.g. this allows making a flow-volume profile using both the inhaled andexhaled volumes and flow rates. Especially, the inhaler may comprise asecond passive acoustic element separate from the first passive acousticelement, serving to generate sound upon air being exhaled into the airinlet or air outlet. Specifically, the inhaler may be arranged toreceive exhaled air through the air outlet, and wherein the flow pathcomprises a valve mechanism arranged to guide exhaled air from the airoutlet via the second passive acoustic element and to the air inlet. Inother implementations, the inhaler is arranged to receive exhaled airvia the air inlet.

The first passive acoustic element can be formed as a monolithic part ofthe housing, if preferred. In some versions, the first passive acousticelement is formed as a monolithic part of a bottom part of the housing.Alternatively, the first passive acoustic element may be a separateelement attached to an inner structure of the housing, thereby allowingthe housing and flow path elements to be re-used in several versions,where only the passive acoustic element itself is replaced to providespecial acoustic characteristics, e.g. suited to specific needs ofspecific users.

E.g. the housing and passive acoustic element may be formed by apolymeric material. In some versions, the inhaler is a disposableproduct, such as being manufactured with a medicament positioned insidethe housing.

The inhaler may comprise a second air inlet or a second air outlet ofthe housing. Especially, in versions suitable for exhalation, a separateair outlet may be provided to guide air out of the housing duringexhalation.

Further sound from the inhaler, i.e. not generated by the passiveacoustic element, can be analysed to provide further informationregarding the use of the inhaler, e.g. to establish if a medicament dosehas been correctly inhaled. E.g. such sound may be sound from theperforating or opening of a medicament container (capsule) inside theinhaler for preparing an inhalation dose.

Even though described as a simple inhaler structure, e.g. for disposableproducts, it is to be understood that more refined versions of theinhaler may be designed to be user for inhalation and/or exhalation athigh precision.

In a second aspect, the invention provides a computer program productbeing adapted to enable a computer system comprising at least onecomputer having data storage means in connection therewith to control amanufacturing system or device, preferably an additive manufacturingsystem or device or a three-dimensional (3D) printing system or device,for producing an inhaler or inhaler add-on device according to any ofthe preceding claims. Such program product may be present on a tangiblemedium and/or on a net based platform arranged for downloading.Especially, 3D printing may facilitate a personalization of the inhaleror inhaler add-on device. It may be possible, e.g. using software designtools, to influence one or more parameters of the first acoustic elementand the gap(s) thereof, so as to personalize the sound generate to matchindividual needs of the user. E.g. to ensure content of low frequencytones to a user who is high frequency hearing impaired.

In a third aspect, the invention provides a system comprising

-   -   an inhaler add-on device according to the first aspect, and    -   a device, such as a smart phone, arranged to capture sound        generated by the inhaler add-on device during an inhalation,        wherein the device comprises a processor arranged to process the        captured sound according to a processing algorithm and to        generate a measure of air flow through the air outlet of the        inhaler in response to the processing algorithm.

Especially, the processing algorithm may be arranged to determinewhether a planned medical dose has been taken correctly, e.g. todetermine if a medicament capsule is empty or not. Further, asmentioned, analysing sound generated by pinning the capsule, it ispossible to determine if the capsule was correctly perforated, and if itwas in a good condition, e.g. had been correctly stored. The device maydisplay or provide audible output to the user accordingly, and/ortransmit a message to an external party accordingly.

Especially, the algorithm comprises performing a spectral analysis ofthe captured sound. E.g. the algorithm may comprise performing a noisesuppression part for suppressing undesired background noise. E.g. theprocessing algorithm may comprise performing a pattern recognition part,e.g. to determine lung performance, diagnosis, improved condition beforeand after treatment, or daily variations in lung function (day/night)etc. The processing algorithm may be arranged to determine a measure ofair flow and to compare this air flow to a predetermined referencevalue, so as to determine if a medical dose has been inhaled accordingto predetermined conditions, such as to determine if a predeterminedmedical dose has been inhaled. The processing algorithm may be designedin accordance with the design of the first passive acoustic element andthe design of the flow path, so as to allow the processing algorithm togenerate a measure of air flow speed in response to the captured sound.Especially, the processing algorithm may be designed to generate ameasure of air flow speed versus time for at least a major part of aninhalation, in response to the captured sound. Sound captured during aninhalation or exhalation using the inhaler may be processed versus time,such as processed in time segments each having a length of such as 1 msto 500 ms.

In a fourth aspect, the invention provides a method for measuringinhaled flow in an inhaler add-on device according to the first aspect,the method comprising

-   -   capturing sound external to the housing generated by the inhaler        add-on device during a user inhaling a medicament through the        air outlet of the inhaler,    -   processing the captured sound according to a processing        algorithm, and    -   generating a measure of inhaled air flow, such as a measure of        inhaled air volume and/or flow speed, through the air outlet of        the inhaler add-on device in response to the processing        algorithm.

In a fifth aspect, the invention provides a computer executable programcode arranged to cause a device to perform the method according to thefourth aspect, when executed on a processor. This may be in the form ofa downloadable application (app) for a smartphone etc. Especially, theprocessing or at least a part of the processing may be cloud based. I.e.a cloud performs processing fully or partially, an evaluation andstoring of data from the inhalations. Hereby, it is not required toinstall software for data processing on the users' device, e.g.smartphone.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only,with reference to the drawings, in which

FIG. 1 illustrates a system embodiment,

FIGS. 2A and 2B show sketches of a stand-alone inhaler embodiment,

FIG. 3 shows the interior part of an alternative to the embodiment ofFIGS. 2A and 2B,

FIG. 4 shows interior part of still another alternative to theembodiment of FIGS. 2A and 2B,

FIGS. 5A and 5B show the lower part of the housing,

FIG. 5C shows the housing being split,

FIG. 6 shows another inhaler embodiment,

FIGS. 7A and 7B show an inhaler housing bottom part similar to theembodiment of FIGS. 5A-5C,

FIGS. 7C and 7D illustrate sound spectra at an inhalation air flow speedof 60 l/min and 40 l/min for the embodiment of FIGS. 7A and 7B,

FIGS. 8A and 8B show an inhaler as in FIGS. 7A and 7B, but here with twogap GP in series and separated by a distance,

FIGS. 8C and 8D illustrate sound at an inhalation air flow speed of 60l/min and 40 l/min for the embodiment of FIGS. 8A and 8C,

FIGS. 9A and 9B show an inhaler similar to FIGS. 8A and 8B, but herewith the passive acoustic element having the two gaps GP in seriesseparated by a shorter distance,

FIGS. 9C and 9D illustrate sound at an inhalation air flow speed of 60l/min and 40 l/min for the embodiment of FIGS. 9A and 9B,

FIGS. 10A and 10B. show an inhaler similar to FIGS. 8 , but here withthe passive acoustic element having the two gaps GP in series havingshorter comb lengths,

FIGS. 11A and 11B show graphs indicating sound amplitude versus air flowspeed

FIGS. 12A and 12B show graphs indicating spectral profile of soundversus air flow,

FIGS. 13A and 13B show sound spectra produced by exhalation through aninhaler embodiment,

FIGS. 14A and 14B show sound spectra produced with a full and emptymedicament capsule in the inhaler,

FIGS. 15A and 15B show sound spectra,

FIG. 16 illustrates steps of a method for measuring inhaled flow in aninhaler,

FIGS. 17A, 17B, and 17C show different views of an inhaler add-onembodiment,

FIGS. 18A and 18B show different views of another inhaler add-onembodiment,

FIGS. 19A, 19B, and 19C show different views of the add-on embodiment ofFIG. 17 ,

FIGS. 20A, 20B, and 20C show different views of an inhaler add-onembodiment with a housing branch where the passive acoustic element ispositioned,

FIGS. 21A, 21B, and 21C show different views of an inhaler add-onembodiment for both inhalation and exhalation, and with two separatepassive acoustic elements.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a block diagram of an inhaler system embodiment with asketch of an inhaler for dispensing a medicament to be inhaled. Theinhaler has a housing H with an air inlet A_I on its bottom part, and anair outlet A_O with a mouthpiece MP for outputting air to be inhaled bya user. The housing H forms a cavity within an outer wall. Inside thiscavity, the housing H defines a flow path FP between the air inlet A_Iand air outlet A_O. A passive acoustic element PAE is arranged in theflow path FP inside the housing H and dimensioned such that air flowpassing it will generate sound S with pre-determined characteristicsdepending on flow speed of air passing the passive acoustic element.This allows acoustic monitoring of air flow passing the first passiveacoustic element external to the housing H, namely by an external deviceSP, such as a smartphone. The passive acoustic element PAE comprises astructure having one or more gaps arranged to be passed by an air flowin order to generate the sound S, in the shown version sound S whichpredominantly exits the air inlet A_I.

The smartphone SP is arranged to capture sound S generated by theinhaler during an inhalation via its built-in microphone. By anapplication program, the smartphone processor P is arranged to processthe captured sound S according to a processing algorithm and to generatea result in the form of a measure of air flow R_M through the air outletA_O of the inhaler in response to the processing algorithm. With suchoutput R_M, the user or other, can be informed e.g. on the display ofthe smartphone SP about the quality of a medicament inhalation, e.g. todetermine if a dose of medicament has been inhaled correctly e.g. usingvisual symbols, such as a green color, a happy face etc. Alternatively,the output R_M may be in the form of an audible signal, e.g. to indicatethat a full medicament dose has been successfully taken.

FIGS. 2A and 2B show sketches of a stand-alone inhaler embodimentarranged for having a medicament compartment or capsule MC arrangedinside the housing H. FIG. 2A shows a transparent drawing, while FIG. 2Bshows only inner part of the housing H with arrows indicating parallelflow paths FP1, FP2 each having their air inlet A_I openings on thebottom of the housing H both ending at the mouth piece MP forming theair outlet A_O. One flow path FP1 has a tube connecting the air inletA_I with a medicament capsule MC, and another tube connects themedicament capsule MC with the air outlet A_O. Another flow path FP2connects the air inlet A_I with the passive acoustic element PAEarranged on a side wall inside the housing H, and it has two gapsseparated by a distance. Thus, air flow is guided to pass the two gapsof the passive acoustic element PAE in a direction parallel with acentre line through the air outlet A_O. The housing H may be formed by apolymeric material, e.g. 3D printed, however other materials may be usedas well.

A mixture of air from the two flow paths FP1, FP2 is thus guided to themouthpiece MP allowing the user to inhale medicament from the medicamentcapsule MC, thus generating sound with pure tone components depending onthe air flow speed of the flow path FP2, but also depending on air flowspeed of the flow path FP1 through the medicament capsule MC. Thereby,it is possible to determine the air flow speed of the flow path FP1 viathe medicament capsule MC and thus the medicament dose delivered duringan inhalation via the air outlet A_O.

In other embodiments, the inhaler has no mouthpiece MP, but instead theair outlet A_O can have an interface arranged for connection to the airinlet of an existing inhaler device. In still another embodiment, theinhaler has a mouthpiece MP, but the air inlet A_I is designed tointerface an air outlet of an existing inhaler device.

FIG. 3 shows interior part of an alternative to the embodiment of FIGS.2A and 2B with the same type of passive acoustic element PAE, but hereit is located in the flow path FP upstream of the medicament compartmentMC, namely with the passive acoustic element PAE positioned at a bottompart of the housing (not shown here for simplicity).

FIG. 4 shows interior part of still another alternative to theembodiment of FIGS. 2A and 2B with the same type of passive acousticelement PAE, but here it is located in the flow path FP downstream ofthe medicament compartment MC, namely inside a tube leading air to theair outlet.

FIGS. 5A-5C show different transparent views of an inhaler embodimentwith a preferred type of passive acoustic element PAE having two sets ofgaps in series and with dimension lines with values in mm indicated.FIGS. 5A and 5B show the lower part of the housing H only with the airinlet A_I at a bottom part, whereas FIG. 5C shows the housing H beingsplit into a bottom part BP including walls forming a cavity with thepassive acoustic element PAE inside, and with an upper opening allowingthe user to split the inhaler by hands for insertion of a medicamentcapsule or the like. A top part TP has a shape matching to close theopening of the bottom part BP, and on its top, the top part TP has amouthpiece MP, thus forming the air outlet A_O of the inhaler. It isalso possible to make different open/closing mechanisms to separate theinhaler's two parts. E.g. such mechanism can be a screwing mechanism, asliding mechanism, or a click lock mechanism.

The passive acoustic element PAE is having: a gap GP being a passagethrough the passive acoustic element PAE with no material being presentin the gap GP. In the shown specific embodiment, two gaps GP areseparated by a distance of D2, e.g. 8 mm, and each gap GP has a widthD1, e.g. 2 mm. The height D3 of the gaps GP may be such as 0.5-3 mm,however preferably 1-2 mm. The length D4 of the teeth defining the gapGP in the shown embodiment is such as 5 mm, wherein a width D5 of eachtooth is such as 2 mm. Especially, the structure of the passive acousticelement PAE may be a monolithic hollow structure forming a flow path toguide air flow to pass the gaps GP.

It is to be understood that all indicated dimensions D1-D5 can be tunedindividually in order to shape the sound generated.

The passive acoustic element PAE can be formed monolithically, e.g.monolithically as a part of the housing H, or it can be manufactured,e.g. 3D printed separately, thus allowing freedom of acoustic design.This may allow a medical doctor to design the passive acoustic elementPAE to match the lung capacity and/or hearing capacity of the user(patient) to use the inhaler. Hereby optimal adaptation to theindividual user can be obtained, thus facilitating that the user canlearn to hear the sound from the inhaler and inhale accordingly, also incase the user has a limited high frequency hearing capacity. It mayalternatively be preferred to injection mold the inhaler, or to 3D printcertain parts of the inhaler, while other parts are injection molded.

FIG. 6 shows another inhaler embodiment, where the bottom part BP is thesame as in FIGS. 5A-5C, but where the top part TP has a second airoutlet A_O2 which is connected to the interior cavity of the housing H.In the shown embodiment, the tube connecting the second air outlet A_O2to the interior cavity of the housing H is perpendicular to a centralaxis through the air inlet A_I and the first air outlet A_O.

The top part TP allows the inhaler to also function as a sound frequencydependent exhale, namely where the air outlet A_O can be used forinhalation as well as exhalation, e.g. to allow testing of the user'slung function. A valve mechanism may be used to ensure that exhalationair outlet is only performed via second air outlet A_O2.

The embodiment shown in FIGS. 5A-5C could as well be used for exhalationby reversing it, or by adding a separate channel for exhalation,depending on preference.

In the following, results of sound spectra for various inhalerembodiments under various conditions will be described.

The influence of the number of gaps on the passive acoustic element inthe inhaler has been tested to demonstrate that a certain number of gapsare preferred to generate a sound, i.e. an acoustic signal, which hascharacteristics which correlate to air flow speed.

FIGS. 7A and 7B show an inhaler housing bottom part similar to theembodiment of FIGS. 5A-5C, but here with a passive acoustic elementhaving only one gap GP.

FIGS. 7C and 7D illustrate sound spectra at an inhalation air flow speedof 60 l/min. and 40 l/min. for the embodiment of FIGS. 7A and 7B. Thesound spectra for the two are clearly different, but without clear anddistinct peaks indicating clear pure tone components, which are easy toidentify with appropriately selected signal processing algorithms.

FIGS. 8A and 8B show again an inhaler as in FIGS. 7A and 7B, but herewith two gap GP in series and separated by a distance (D2 referring toFIGS. 5A, 5B) of such as 8 mm. The shape and size of each single gap GPis identical with the gaps in FIGS. 7A and 7B.

FIGS. 8C and 8D illustrate sound at an inhalation air flow speed of 60l/min. and 40 l/min. for the embodiment of FIGS. 8A and 8B. Two clearnarrow spectral peaks are seen at 8 and 16 kHz at air flow speed 60l/min., whereas corresponding peaks at 40 l/min. are located at about6.5 and 13 kHz. Thus, this embodiment with two gaps GP allows easyspectral correlation to air flow speed. It is to be used that more gapsGP in series than two may be used, e.g. 3, 4, 5, if preferred. Theoverall sound pressure level, i.e. the amplitude, is similar for theembodiments in FIGS. 7A-7B and 8A-8B, but due to the narrow spectralpeaks in the sound signal, two sets of gaps are preferred.

FIGS. 9 a and 9 b show an inhaler similar to FIGS. 8A and 8B, but herewith the passive acoustic element having the two gaps GP in seriesseparated by a shorter distance (D2 referring to FIGS. 5A, 5B), namelysuch as 2 mm.

FIGS. 9C and 9D illustrate sound at an inhalation air flow speed of 60l/min. and 40 l/min. for the embodiment of FIGS. 9A and 9B. Compared toFIGS. 8C and 8D, spectral peaks are seen at 60 l/min, but at lowerfrequency. Further, at lower flow speed 40 l/min., the shorter spacingbetween the gaps GP results in less distinct peaks compared with theinhaler embodiment of FIGS. 8C and 8D. In conclusion, the optimumdistance between gaps GP should be selected according to individualtargets.

FIGS. 10A and 10B. show an inhaler similar to FIGS. 8 , but here withthe passive acoustic element having the two gaps GP in series havingshorter comb lengths (D4 referring to FIGS. 5A, 5B), namely such as 3 mmcompared to about 5 mm in the previous examples. This is obtainedcompared to the previous embodiments, by the passive acoustic elementhaving the same overall width D6, but with a larger gap distance D1between each set of teeth than in the previous embodiments.

FIGS. 10C and 10D illustrate sound at an inhalation air flow speed of 60l/min. and 40 l/min. for the embodiment of FIGS. 10A and 10B. As seen,compared to FIGS. 8C and 8D the spectral peaks can be observed, but theyare less pronounced and distinct than in the embodiment of FIGS. 8C and8D. Thus, an optimal gap length to achieve a desired sound has to beselected, e.g. depending on inhaler material, resolution (3D printing orother technologies) and the location of the passive acoustic elementwithin the inhaler design.

To test the effect of 3D printing resolution on the resulting soundproduced by the inhaler, the embodiment shown in FIG. 6 has been printedin two versions: one which is printed by a high resolution printerhaving a resolution of 60 μm (a high-end commercial 3D printer), and onewhich is printed by a low resolution printer having a resolution of 300μm (such as Makerbot or Ultimaker 3D printer). The inhaler was testedwithout the mouth piece. Here, it was observed that the high resolutioninhaler produced sound having a narrow peak with double the amplitude ofthe low resolution inhaler at a flow rate of 40 l/min. It is believedthis is due to the higher printing resolution and hence more welldefined and sharp edges of the gaps of the passive acoustic element.Thus, to produce the most distinct sound from the inhaler, which allowsthe most easy signal processing to correlate to air flow speed, it ispreferred that a passive acoustic element with rather sharp edged on thegap(s) is used. In case of 3D printing, this appears to require aprinting resolution better than 2-300 μm. Further, with a bettermanufacturing resolution, a more accurate geometry according to theselected design, e.g. length and width of the gap(s) (D4, D5 referringto FIGS. 5A, 5B).

FIGS. 11A and 11B show graphs indicating sound amplitude versus air flowspeed for the mentioned high resolution (60 μm) and low resolution (300μm) inhaler versions. Both generally show increased sound amplitude withincreasing air flow speed, but in general the sound amplitude producedby the high resolution inhaler is higher than the sound amplitudeproduced by the low resolution inhaler.

FIGS. 12A and 12B show graphs indicating spectral profile of soundversus air flow speed for the mentioned high resolution (60 μm) and lowresolution (300 μm) inhaler versions. The two inhalers both show severalpeaks of different frequency for each flow rate, although a cleartendency in the frequencies as a function of flow rate was difficult todiscern. It was observed that frequencies were generally higher for thelow resolution version compared to the high resolution version.

A suitable processing algorithm, e.g. based on a training of a machinelearning algorithm, can, regardless of possible chaotic air flow speed,be used to compute a measure of air flow speed based on the acousticcharacteristics of the captured sound.

FIGS. 13A and 13B show spectra for sound produced by the effect ofreversing the inhaler of FIG. 6 , so as to test its function forexhaling into the inhaler. The high resolution version inhaler was usedfor this test, again without the mouth piece. As seen, a clear signalwith distinctive peaks is observed both at an air flow speed of 60l/min. and at 20 l/min. This demonstrated that the inhaler can also beused for exhalation, even though in the test, air was driven from theother end of the device. Blowing or exhaling air, however, shows similarresults and can be performed from both ends of the inhaler.

The influence of adding a medicament capsule into the cavity of theinhaler housing was then assessed, again for the mentioned highresolution inhaler version. A commercial drug product with a capsulecontaining a drug dose intended for inhalation was placed in the inhalerand tested.

FIGS. 14A and 14B show sound spectra at 60 l/min. air flow speed for thefull and empty medicament capsule. Inhalation using an unpierced capsuleshowed that the rotation of the capsule inside the inhaler results insignificant fluctuations in the produced sound, and thus disrupts to acertain degree the spectral peaks otherwise observed. It can be observedfrom inspecting the sound signal as a function of time (not shown) thatthe sound fluctuates due to the rotational motion of the capsule. Thereare, however, still peaks that can be used for analysis of the air flowrate. The same trend was observed at different flow rates. With an emptycapsule, the inhaler produces sound with much more distinct spectralpeaks compared with the full capsule. The same profile was observed atdifferent air flow speeds. For the empty capsule, fluctuations due tothe rotation of the capsule were minor and did not have any influence onthe captured sound. Although the capsule rotation sound may beconsidered as a disturbing effect on the sound from the inhalation, itcan also provide information about the dosing of the medicament,including capsule emptying, and e.g. the rotational speed of the capsulemay provide additional indications when analysed as a separate soundsignal.

This demonstrates that it is easy to distinguish between a full and anempty capsule based on the sound captured or recorded from outside theinhaler. This is both due to differences in sound amplitude, andfrequencies and the fluctuating patterns. This can thus be used tomonitor correct administration of the dose using the inhaler and ensurethat the patient is taking the required drug dose. The fluctuations inthe signal can also be mitigated, if desired, by placing the passiveacoustic element in a parallel flow path, e.g. as the inhaler embodimentin FIGS. 2A and 2B, where the same air does not pass over both thecapsule chamber and passive acoustic element. It is possible that thesound from the rotating capsule can be captured by the soundcapturer/recorder without influencing the sound produced by air flowpassing the passive acoustic element. However, it may also beadvantageous to make use of this fluctuating signal from the acousticelement, for monitoring purposes.

FIGS. 15A and 15B show graphs with examples of frequency analyses versustime profiles for sound generated by an inhaler produced with a highresolution (60 μm), i.e. indication of amplitude at various frequenciesversus time. Black indicates low amplitude, and white indicates highamplitude. FIG. 15A shows the result for the inhaler exposed to aconstant air flow of 60 l/min., while FIG. 15B shows the result for thesame inhaler exposed to inhalation by a healthy male volunteer. FIGS.15A and 15B illustrate the differences in signal over time observed whenthe acoustic inhaler is used. On one hand, the fixed flow rate using avacuum pump (FIG. 15A) shows that a fixed flow rate can produce a fixedand constant sound while the acoustic element is exposed to the givenpressure/flow. On the other hand, it also shows that an inhalation froma person can result in a more dynamic flow and sound profile, where thesound profile has more information that can be further processed andevaluated.

FIG. 16 shows steps of a method for measuring inhaled flow in an inhaleror inhaler add-on device according to the invention. The methodcomprises capturing sound C_S generated by the inhaler or inhaler add-ondevice during an inhalation. The sound is captured external to thehousing, e.g. at a distance of such as 1 cm to 1 m, or 10 cm to 1 m,e.g. during a user inhaling a medicament through the air outlet of theinhaler. This can be done by the built-in microphone of a portablecommunication device, e.g. a smartphone. Next step is processing P_S thecaptured sound according to a processing algorithm. Finally the step ofgenerating G_AF, a measure of inhaled air flow is performed, such as ameasure of inhaled air volume and/or flow speed through the air outlet.In a more simple version, an output can be generated from the capturingdevice being such as a smartphone, indicating to the user and/or toanother party, if a medicament dose has been inhaled through the airoutlet or not.

FIGS. 17A, 17B, and 17C show different views of an inhaler add-onembodiment ADV and an inhaler device INHD, e.g. a metered dose inhalerwith an actuator on its top part for triggering an inhaled dose ofmedicament. Following the principles of the embodiments in the forgoing,the inhaler add-on device ADV has a housing H with a mouth piece MP inone end, and a fitting part FPT at the opposite end. The mouth piece MPis arranged for contact with the user's mouth during inhalation, and thefitting part FPT is arranged for connection to the inhaler INHD byattachment of the fitting part FPT to an air outlet pipe O_P of theinhaler INHD, so as to lock the add-on device ADV in position relativeto the inhaler INHD for use.

As seen, the fitting part FPT is shaped so as to receive the air outletpipe O_P of the inhaler and to allow locking of the position of theinhaler add-on device to the inhaler upon insertion of the outlet pipeof the inhaler into the fitting part FP of the inhaler add-on deviceADV. The mouth piece MP has an outer circular or elliptical crosssectional area which is smaller than an outer cross sectional area ofthe fitting part FPT, and the same applies to inner cross sectionalareas, i.e. the part of the housing H constituting the flow path betweeninhaler INHD and mouth piece MP. The size of the mouth piece MP can bedimensioned so as to fit the user, and it is not in any way limited bythe dimensions of the acoustic element PAE.

The fitting part FP is preferably shaped to fit to the shaped anddimensions of the outlet pipe O_P of the inhaler INHD, so as to allowthe user to simply press the add-on device ADV onto the outlet pipe O_Pto lock its position for use. The user can either leave the add-ondevice ADV on the inhaler INHD for the next use, or take off the add-ondevice ADV e.g. for replacement, such as the add-on device ADV being adisposable. Alternatively, the inhaler INHD is a single-use device,while the add-on device ADV can be used multiple times. E.g. both theinhaler and the add-on may be used multiple times and for instance usedfor the same time span, e.g. 30 doses inhaled over 30 days etc. Theadd-on device can also be taken off and cleaned if needed, and it can bewashed and cleaned which may be possible especially in cases where theadd-on device if formed by a monolithic polymeric element.

The add-on device can also be taken off and cleaned if needed. It can intheory be washed and cleaned as it most likely only consists of aplastic monolith The passive acoustic element PAE is arranged inside themouth piece MP and with one opening connected to the opening of themouthpiece MP and the opposite opening connected to a flow path insidethe housing H. This means that the medicinal dose will pass through thepassive acoustic element PAE in this case. Depending on the medicationtaken this could provide a subtle but distinct and different soundsignal when the medicinal dose goes through the passive acoustic elementPAE. The housing H is shaped to provide a straight flow path between themouth piece MP and the fitting part FP. Of course, depending on thedesign of the inhaler INHD to fit with the add-on device, the flow pathbetween fitting part FP and mouth piece MP may be bend or curved.

FIGS. 18A and 18B show another inhaler add-on embodiment similar to theone in FIGS. 17A-17C, but shaped to fit to another type of inhaler INHD,here a dry powder type inhaler without an actuator, thus having adifferently shaped fitting part FPT arranged to shape the outlet pipeO_P of this inhaler INDH.

FIGS. 19A, 19B, and 19C show larger views of the add-on embodiment ofFIG. 17A. Here, the specific passive acoustic element PAE in the mouthpiece MP with two gaps is shown. It is to be understood that the passiveacoustic element PAE can be designed differently, as already describedin previous embodiments.

FIGS. 20A, 20B, and 20C show different views of an inhaler add-onembodiment ADV which is similar to the one in FIGS. 19A-19B, except thatthe passive acoustic element PAE is here placed in a housing branch HB,and not in the mouth piece MP. The housing branch HB is designed toprovide only limited part of an air flow through the mouth piece, suchas 5-50%, e.g. 5-15%, of an air flow through the mouth piece MP, whichmay be advantageous to avoid high air flows and e.g. disturbance ofmedicaments from the inhaler.

As seen, the passive acoustic element PAE is arranged in an air flowpath between an opening of the housing branch HB and air flow inside thehousing H, i.e. the housing branch has an opening to the environmentwhich is separate from the openings in the mouth piece MP and theopening in the fitting part FP. As seen, in this embodiment, the housingbranch HB is designed so that the passive acoustic element PAE isarranged in a flow path with a flow direction being perpendicular to themain flow path direction in the mouth piece MP, and the flow directionbetween the fitting part FP and the mouth piece MP.

FIGS. 21A, 21B, and 21C show different views of an inhaler add-onembodiment ADV similar to the one in FIG. 19A, but here the mouth pieceMP is arranged to receive exhaled air, so as to allow acousticmonitoring of exhaled air flow external to the add-on device upon a userexhaling air into the mouth piece MP. Thus, in this embodiment ADV,acoustic monitoring of both inhalation and exhalation is possible.

Two separate passive acoustic elements PAE, PAE2 are used, one PAE forinhalation and one PAE2 for exhalation by means of a first valve V1arranged to block exhaled air flow from passing the first passiveacoustic element PAE, and a second valve V2 arranged to block inhaledair flow from passing the second passive acoustic element PAE2. Boldarrows indicate inhalation and exhalation flow directions through thedevice ADV. For exhalation, the second passive acoustic element PAE2 isconnected to receive air flow in the mouth piece opening, while theopposite end is connected to an opening of the housing H where thesecond valve V2 is positioned to block incoming air during inhalationthrough the mouth piece MP.

As seen, both passive acoustic elements PAE, PAE2 are arranged insidethe mouth piece MP part of the housing H, and these two elements may bedifferent or identical. Other positions of the passive acoustic elementsPAE, PAE2 may be chosen, e.g. a combination of the ones shown inembodiments in FIGS. 19A and 20A.

In general, outer shape and dimensions of an inhaler add-on deviceshould be fitted to an actual inhaler type, shape and dimension.

In the following, inhaler embodiments of the invention will be definedas E1-E10.

E1. An inhaler for dispensing a medicament to be inhaled, the inhalercomprising

-   -   a housing (H) comprising an air inlet (A_I), and an air outlet        (A_O), such as comprising a mouthpiece (MP) for outputting air        to be inhaled by a user, wherein the housing (H) defines a flow        path (FP) between the air inlet (A_I) and air outlet (A_O), and    -   a first passive acoustic element (PAE) arranged in the flow path        (FP) inside the housing (H) and dimensioned such that air flow        passing the first passive acoustic element (PAE) will generate        sound (S) with pre-determined characteristics depending on flow        speed of air passing the first passive acoustic element (PAE),        so as to allow acoustic monitoring of air flow passing the first        passive acoustic element (PAE) external to the housing (H),

wherein the first passive acoustic element (PAE) comprises a structurehaving one or more gaps arranged to be passed by an air flow.

E2. Inhaler according to E1, wherein the one or more gaps are shaped andseparated by a distance (D2) so as to generate sound depending on airflow speed with pre-determined characteristics comprising at least oneof: amplitude, and spectral components.

E3. Inhaler according to E2, wherein the one or more gaps are shaped andseparated by a distance (D2) so as to generate sound (S) depending onflow speed with pre-determined characteristics comprising at least onespectral peak, preferably 2-4 spectral peaks.

E4. Inhaler according to any of E1-E3, wherein said one or more gaps arestraight gaps which are perpendicular or substantially perpendicular toa direction of air flow passing the first passive acoustic element(PAE).

E5. Inhaler according to any of E1-E4, wherein the first passiveacoustic element (PAE) comprises a structure having teeth defining oneor more gaps (GP) between them, wherein the one or more gaps (GP) beinga passage through the structure with no material being present in thegap (GP).

E6. Inhaler according to any of E1-E5, wherein the first passiveacoustic element (PAE) is positioned in the flow path (FP) downstream ofan inhaler medicament compartment (MC) for providing medicament to beinhaled.

E7. Inhaler according to any of E1-E6, wherein the air inlet (A_I) orair outlet (A_O) of the housing (H) is arranged for connection to aseparate device, wherein said separate device comprises a compartmentcomprising a medicament to be inhaled.

E8. Inhaler according to E1-E7, further being arranged to receiveexhaled air via the air inlet (A_I) or the air outlet (A_O), so as togenerate sound with pre-determined characteristics depending on flowspeed of air passing the first passive acoustic element (PAE), so as toallow acoustic monitoring of air flow passing the first passive acousticelement (PAE) external to the housing (H) upon a user exhaling air intothe air inlet (A_I) or air outlet (A_O).

E9. Inhaler according to E1-E9, wherein the first passive acousticelement (PAE) is formed as a monolithic part of the housing H.

E10. A system comprising an inhaler according to any of E1-E9, and

-   -   a device (SP), such as a smart phone, arranged to capture        sound (S) generated by the inhaler during an inhalation, wherein        the device comprises a processor (P) arranged to process the        captured sound (S) according to a processing algorithm and to        generate a measure of air flow through the air outlet (A_O) of        the inhaler in response to the processing algorithm, preferably        so as to determine if a dose of medicament has been inhaled.

Such inhaler device and system as in embodiments E1-E10 is advantageous,since it has been proven to be possible to provide an inhaler with avery simple structure, including the passive acoustic element withstructured gaps, which allows e.g. 3D printing of the entire inhaler.This allows the inhaler to be manufactured as a disposable productand/or to be produced at the point of need, e.g. by the user or at ahospital etc. The inhaler does not require any electrical componentsinside or on the housing, since the sound is generated by a passiveacoustic element, in the same manner as a whistle.

To sum up, the invention provides an inhaler or an add-on device for aninhaler for dispensing a medicament to be inhaled. The inhaler or add-ondevice has a housing H with an air inlet A_I, and an air outlet A_O foroutputting air to be inhaled by a user. The housing H defines a flowpath FP between the air inlet A_I and air outlet A_O, and a passiveacoustic element PAE is arranged in this flow path FP inside the housingH. The passive acoustic element PAE has a structure having one or moregaps arranged to be passed by an air flow and it is dimensioned suchthat air flow passing it will generate sound S with pre-determinedcharacteristics depending on the air flow speed. This allows acousticmonitoring of air flow passing the first passive acoustic element PAEexternal to the housing H by capturing and processing sound generated.

Although the present invention has been described in connection with thespecified embodiments, it should not be construed as being in any waylimited to the presented examples. The scope of the present invention isto be interpreted in the light of the accompanying claim set. In thecontext of the claims, the terms “including” or “includes” do notexclude other possible elements or steps. Also, the mentioning ofreferences such as “a” or “an” etc. should not be construed as excludinga plurality. The use of reference signs in the claims with respect toelements indicated in the figures shall also not be construed aslimiting the scope of the invention. Furthermore, individual featuresmentioned in different claims, may possibly be advantageously combined,and the mentioning of these features in different claims does notexclude that a combination of features is not possible and advantageous.

1. (canceled)
 2. An inhaler add-on device for add-on to an inhaler fordispensing a medicament to be inhaled, the inhaler add-on devicecomprising a housing comprising an air inlet, and an air outlet, such ascomprising a mouthpiece for outputting air to be inhaled by a user,wherein the housing defines a flow path between the air inlet and airoutlet, wherein the housing is configured for connection to the inhaler,and a first passive acoustic element arranged in the flow path insidethe housing and dimensioned such that air flow passing the first passiveacoustic element will generate sound with pre-determined characteristicsdepending on flow speed of air passing the first passive acousticelement, so as to allow acoustic monitoring of air flow passing thefirst passive acoustic element external to the housing, wherein thefirst passive acoustic element comprises a structure having one or moregaps arranged to be passed by an air flow, and wherein the one or moregaps are shaped and separated by a distance so as to generate sounddepending on air flow speed with pre-determined characteristicscomprising at least spectral components.
 3. The inhaler add-on deviceaccording to claim 2, wherein the housing and the first passive acousticelement is formed as one single polymeric material.
 4. The inhaleradd-on device according to claim 2, wherein the air inlet or air outletof the housing is arranged for connection to a separate device, whereinsaid separate device comprises a compartment comprising a medicament tobe inhaled.
 5. The inhaler add-on device according to claim 2, whereinthe first passive acoustic element is a separate element attached to aninner structure of the housing, thereby allowing the housing and flowpath elements to be re-used in several versions, where only the passiveacoustic element itself is replaced.
 6. The inhaler add-on deviceaccording to claim 2, wherein the one or more gaps are 0.5-3 mm wide,the length of the one or more gaps are 2-10 mm, and/or the materialthickness around the one or more gaps is 0.5-3 mm.
 7. The inhaler add-ondevice according to claim 2, wherein the one or more gaps have sharpedges, such as edges formed by 90° corners, or at least corners of suchas 40°-140°, or such as 70°-110°.
 8. The inhaler add-on device accordingto claim 2, wherein the one or more gaps are rectangular in shape with alength of 2-5 times the width.
 9. The inhaler add-on device according toclaim 8, wherein the one or more gaps have two parallel walls and onetapered end.
 10. The inhaler add-on device according to claim 2, whereinthe inhaler add-on device is formed as one or two rows of substantiallyrectangular shaped parallel gaps, each having a length of at 2-5 timesthe width.
 11. The inhaler add-on device according to claim 2, whereinthe first passive acoustic element has surfaces in or adjacent to theone or more gaps which have surface morphology and surface material,which can both be selected depending on the type of gap(s) selected andwhich specific sound is preferred.
 12. The inhaler add-on deviceaccording to claim 2, wherein the first passive acoustic element has aplurality of sets of gaps separated by difference distances.
 13. Theinhaler add-on device according to claim 2, wherein the first passiveacoustic element is configured to generate sound predominantly within anaudible level and in an audible frequency range, thereby allowing theuser to hear tones indicative of inhalation air flow speed.
 14. Theinhaler add-on device according to claim 2, wherein the first passiveacoustic element is configured to generate sound predominantly withfrequencies above 14 kHz, so as to be generally inaudible, thus allowingthe inhaler to be used in public without generating any offensive ordisturbing tones.
 15. The inhaler add-on device according to claim 2,wherein the first passive acoustic element is configured to generatesound with audible and inaudible spectral components for air flow speedsin the relevant range for inhalation.
 16. The inhaler add-on deviceaccording to claim 2, wherein the first passive acoustic element and theinhaler medicament compartment are arranged in respective parallel flowpaths.
 17. The inhaler add-on device according to claim 16, wherein theair inlet is split into two separate openings each guiding air to therespective parallel flow paths, to allow the flow path around thepassive acoustic element irrespective of an inhalation flow path. 18.The inhaler add-on device according to claim 2, wherein the firstpassive acoustic element comprises a static structure with no movingparts.
 19. The inhaler add-on device according to claim 2, wherein theinhaler add-on device is 3D printed.
 20. The inhaler add-on deviceaccording to claim 2, wherein the first passive acoustic element is 3Dprinted with a 3D printed resolution which is better than 200 μm,preferably better than 100 μm.
 21. The inhaler add-on device accordingto claim 1, wherein the first passive acoustic element is anon-vibrating structure configured to generate sound by movement of airpassing the passive acoustic element.
 22. The inhaler add-on deviceaccording to claim 1, wherein the one or more gaps are shaped andseparated by a distance so as to generate sound depending on flow speedwith pre-determined characteristics comprising at least one spectralpeak.
 23. The inhaler add-on device according to claim 1, wherein saidone or more gaps are straight gaps which are perpendicular orsubstantially perpendicular to a direction of air flow passing the firstpassive acoustic element.
 24. The inhaler add-on device according toclaim 1, wherein the first passive acoustic element comprises astructure having teeth defining one or more gaps between them, whereinthe one or more gaps are a passage through the structure with nomaterial being present in the gap.
 25. The inhaler add-on deviceaccording to claim 1, wherein the first passive acoustic element ispositioned in the flow path downstream of an inhaler medicamentcompartment configured to provide and inhalable medicament.
 26. Theinhaler add-on device according to claim 1, wherein the first passiveacoustic element is positioned in the flow path upstream of an inhalermedicament compartment configured to provide an inhalable medicament.27. The inhaler add-on device according to claim 1, wherein said deviceis configured to receive exhaled air via the air inlet or the airoutlet, so as to generate sound with pre-determined characteristicsdepending on flow speed of air passing the first passive acousticelement, so as to allow acoustic monitoring of air flow passing thefirst passive acoustic element external to the housing upon a userexhaling air into the air inlet or air outlet.
 28. The inhaler add-ondevice according to claim 1, wherein the first passive acoustic elementis formed as a monolithic part of the housing.
 29. The inhaler add-ondevice according to claim 1, wherein the housing and the first passiveacoustic element is formed as a monolithic element.
 30. The inhaleradd-on device according claim 1, wherein the first passive acousticelement is arranged in a flow path so as to receive a limited part of anair flow.
 31. The inhaler add-on device according to claim 1, whereinthe first passive acoustic element is arranged in an air flow pathbetween an opening of the housing and air flow inside the housing. 32.The inhaler add-on device according to claim 1, wherein the firstpassive acoustic element is arranged in a flow path with a direction,which is perpendicular to a flow path direction.
 33. The inhaler add-ondevice according to claim 1, comprising a first valve configured toblock exhaled air flow from passing the first passive acoustic element.34. The inhaler add-on device according to claim 1, further comprising amicrophone configured to capture sound from the first acoustic passiveelement, and further configured to transmit data in response to capturedsound using a wired or wireless connection to an external device. 35.The inhaler add-on device according to claim 33, wherein the microphone,and a processor circuit connected thereto are configured to transmitsaid data, and a battery for powering the processor circuit, are housedin a second housing separate from the first housing, optionally thesecond housing is configured to attach to the inhaler.
 36. A computerprogram configured to control a manufacturing system or devicecomprising at least one computer having a data storage configured togenerate an inhaler add-on device according to any claim
 1. 37. A systemcomprising: an inhaler add-on device according to claim 1, and a deviceconfigured to capture sound generated by the inhaler add-on deviceduring an inhalation, wherein the device comprises a processorconfigured to process the captured sound according to a processingalgorithm and to generate a measure of air flow through the air outletof the inhaler in response to the processing algorithm.
 38. A method formeasuring inhaled flow in an inhaler add-on device according to claim 1,the method comprising: capturing sound external to the housing generatedby the inhaler add-on device during a user inhaling a medicament throughthe air outlet of the inhaler add-on device, processing the capturedsound according to a processing algorithm, and generating a measure ofinhaled air flow through the air outlet of the inhaler add-on device inresponse to the processing algorithm.
 39. A computer executable programcode arranged to cause a device to perform the method according to claim37, when executed on a processor.